积灰对光伏组件发电性能影响的研究

提出了一种评估积灰对光伏组件发电性能影响的有效方法及其数学模型。该方法通过监测光伏发电效率和光伏组件连续积灰的灰尘密度值,建立了输出功率退化数学模型,从理论上说明光伏组件表面积灰对发电效率的影响,为定量研究灰尘影响发电效率提供了理论支撑。搭建了试验平台进行试验研究,验证了输出功率退化数学模型的精度。     

灰尘沉积对光伏组件发电性能的影响

积灰会影响到光伏组件对太阳辐照量的接收,从而造成输出功率下降。针对大理地区的气候特点,通过模拟与实测相结合的方法,对该地区积灰及雨水冲刷对组件发电性能的影响进行了研究。研究结果表明少雨的1—5月份,各月积灰造成的组件输出功率的衰减为11.4%～13.3%,组件积灰较长时间后输出功率下降明显,积灰90日后,输出功率下降21.6%。雨水冲刷研究结果表明,经历6—10月份的雨水冲刷后,测试积灰组件相对发电效率由78.1%上升至90.0%,雨水对清洁光伏组件表面灰尘效果明显。     

反光材料对采用双面光伏组件的屋顶光伏电站发电性能的影响分析

通过搭建实证系统,研究了2种防水卷材和3种白漆对双面光伏组件发电量的影响,为工商业屋顶光伏电站采用双面光伏组件的设计提供了理论支持;并将各种材料的成本和电站发电量收益情况进行了对比分析,获得了较为优化的解决方案.     

积灰性质对光伏组件输出性能影响研究

该文针对光伏电站现场的灰成分,进行不同粒径和不同成分积灰对光伏组件输出性能影响实验,基于实验数据建立积灰密度、太阳辐照度与光伏组件输出功率以及工作电流的拟合模型。实验结果表明,光伏组件开路电压和最佳工作电压受积灰性质波动较小,光伏组件最佳工作电流受积灰性质影响较大,光伏组件最大输出功率衰减主要是受到光伏组件最佳工作电流降低的影响,积灰粒径分布对光伏组件最大输出功率和最佳工作电流的影响远大于积灰成分的影响。     

并网光伏电站关键部件的运行性能分析

简要概述了50kW大型并网光伏电站的系统构成;通过一段时间的运行,对该电站的一些关键部件进行性能评价。分析结果表明：电站的光伏组件设计合理,并网逆变器具有较高的转换效率。     

智能清扫机器人在屋顶分布式光伏电站中的应用

随着国家“双碳”战略的实施,分布式光伏电站作为集中式光伏电站的有效补充应用形式得到了快速发展。由于分布式光伏电站多建于工厂、园区、车站等建筑的屋顶,在进行光伏组件清洗时面临清洗人员高处坠落风险大、清洗次数多等困难。以某屋顶分布式光伏电站为例,首先对传统人工清洗方式存在的问题进行分析,然后针对这些问题提出利用智能清扫机器人进行清扫的解决方案,并对智能清扫机器人实际应用效果进行验证。研究结果显示：采用智能清扫机器人清扫的光伏阵列的总发电量可提升21.2%,在该提升幅度下,对于5.324 MW的屋顶分布式光伏电站而言,使用智能清扫机器人清扫可比采用人工清洗方式清扫每月多提升63.74万kWh的发电量,每年增加的发电量收益为50.77万元,1～2年即可回收智能清扫机器人的初始投资成本。以期该研究结果为分布式光伏电站提升运维效率、降低运维成本提供参考。     

光伏封装材料对组件性能的影响分析

通过光伏组件不同封装材料和封装方式的常规测试及老化测试对比．讨论了不同材料和不同封装方式对光伏组件性能的影响差异,重点分析了PIB封装密封材料在组件封装中的作用及其对组件的影响。     

入射角对大尺寸光伏组件性能影响的实验研究

选取3种尺寸不同的182半片双玻PERC单晶硅光伏组件(编号分别为A、B、C),在室内测试条件下,首先测试光伏组件A和光伏组件B对不同入射角的响应特性,用于分析入射角对不同尺寸光伏组件性能的影响;然后测试光伏组件C在初始状态和其表面有轻微灰尘时的电性能、反射率,以及其在不同入射角下的响应特性,用于分析轻微灰尘对大尺寸双玻光伏组件性能的影响。研究结果表明：1)入射角在-85°～85°之间时,随着入射角的增大,两种大尺寸双玻光伏组件的短路电流减小幅度基本一致。这意味着不同入射角下短路电流的减小幅度不受光伏组件尺寸的影响。2)当入射角小于60°时,两种大尺寸双玻光伏组件的相对透光率都接近1,且尺寸相对较大的光伏组件的相对透光率整体略微偏高。3)当入射角超过70°时,光伏组件的相对透光率急剧减小,将导致输出电流损失急剧增大。因此,在光伏组件实际使用过程中,应避免入射角出现超过70°的情况。4)在有积灰的3种不同反射率下,光伏组件开路电压的变化不大,说明不同积灰状态均对光伏组件开路电压的影响较小,但对短路电流的影响却十分明显;随着反射率的增加,光伏组件C的短路电流逐渐减小,最大功率也在逐渐减小。但当积灰不多,反射率不够高时,应在清洗积灰成本和发电效益之间寻求平衡。     

光伏组件选型对光伏系统发电量的影响

深入研究了不同种类光伏组件在不同天气条件下的发电特性以及相同种类不同厂家光伏组件的发电特性。实验结果表明不同种类太阳电池在不同季节的发电特性存在明显差异。晶体硅和CIGS(铜铟镓硒)电池冬季发电量明显高于硅薄膜电池,最多可多发电10%左右;随时间推移,三者之间的差异先逐渐减小后增加,到夏季硅薄膜反超多晶硅和CIGS,最多可多发电20%左右。同时,结合光辐照度、温度、湿度等天气资料,测试结果表明:晶体硅和CIGS更适合辐照量高、温度低、湿度小的中国北部地区;硅薄膜在辐照度不高、温度高、湿度大的中国南部大部分地区具有更高发电量。     

基于户外并网光伏电站运行数据的双面光伏组件发电性能研究

在湖南省湘潭地区某建筑屋顶建设光伏电站实证平台,跟踪分析了该平台中户外并网光伏电站在2020年10月—2021年9月这1年间的运行实证数据。总结了光伏电站所在地的气候情况及实测的太阳辐照情况,有针对性地对比了传统单面光伏组件与不同类型双面光伏组件的发电表现,分析了采用不同类型跟踪支架系统的双面光伏组件的发电量增益情况。相关结果可为光伏产品选型和当地光伏发电系统设计提供有效的数据支撑。     

Thermal performance of a novel rooftop solar micro-concentrating collector

Concentrating solar thermal systems offer a promising method for large scale solar energy collection. Although concentrating collectors are generally thought of as large-scale stand-alone systems, there is a huge opportunity to use novel concentrating solar thermal systems for rooftop applications such as domestic hot water, industrial process heat and solar air conditioning for commercial, industrial and institutional buildings. This paper describes the thermal performance of a new low-cost solar thermal micro-concentrating collector (MCT), which uses linear Fresnel reflectors, and is designed to operate at temperatures up to 220 °C. The modules of this collector system are approximately 3 m long by 1 m wide and 0.3 m high. The objective of the study is to optimise the design to maximise the overall thermal efficiency. The absorber is contained in a sealed enclosure to minimise convective losses. The main heat losses are due to natural convection inside the enclosure and radiation heat transfer from the absorber tube. In this paper we present the results of a computational and experimental investigation of radiation and convection heat transfer in order to understand the heat loss mechanisms. A computational model for the prototype collector has been developed using ANSYS–CFX, a commercial computational fluid dynamics software package. The numerical results are compared to experimental measurements of the heat loss from the absorber, and flow visualisation within the cavity. This paper also presents new correlations for the Nusselt number as a function of Rayleigh number.     

Aeolian dust deposition on photovoltaic solar cells: the effects of wind velocity and airborne dust concentration on cell performance

Wind tunnel experiments were conducted to investigate the effect of wind velocity and airborne dust concentration on the drop of photovoltaic (PV) cell performance caused by dust accumulation on such cells. Performance drop was investigated at four wind velocities and four dust concentrations. I–V characteristics were determined for various intensities of cell pollution. The evolutions of the short circuit current, the open circuit voltage, the maximum power, the reduction of solar intensity received by the cells, and the fill factor variation with increasing cell pollution were examined. The deposition (and accumulation) of fine aeolian dust on PV cells significantly affects the performance of such cells. Wind velocity has an important impact on cell performance drop, since the drop is larger in high winds than in low winds. However, the wind also affects the sedimentological structure of the dust coating on the cell, resulting in a higher transmittance (of light) for coatings created during high winds. The wind tunnel experiments indicate that the former effect is more important than the latter, which means that, in general, the drop in PV cell performance due to dust accumulation is larger as wind speed increases. Airborne dust concentration also affects the drop in PV cell performance, since high dust concentrations lead to a higher accumulation on the cell. Contrary to wind speed, airborne dust concentration does not seem to affect the sedimentological structure of dust coatings (with respect to light transmittance) on PV cells.     

Effect of dust deposition on the performance of a solar desalination plant operating in an arid desert area

The performance of a solar desalination plant (whether using thermal or photovoltaic collectors) is influenced by the ability of the glazing system to transmit solar radiation to the collector absorption surface. This ability is influenced by such factors as the intensity of solar radiation, the transmittance of the collector glazing, the tilt angle of the absorbing surface, the operating parameters of the plant, the properties of the materials of construction, etc. This paper discusses the influence of dust deposition on the evacuated tube collector field on the operating performance of the solar desalination plant at Abu Dhabi, UAE. This plant has a collector field area of 1864 m² of absorber surface and an MED (multiple effect distillation) unit for seawater desalination with a capacity of 120 m³/day of distilled water. The reduction in transmittance due to dust deposition on the amount of heat collected has been measured and its influence on the distillate production has been estimated using the computer simulation program SOLDES which has been verified previously as an effective tool for predicting the operating performance of similar plant designs. The frequency of high-pressure water jet cleaning on the performance of the plant was also investigated. It was found that dust deposition and its effect on plant performance depend strongly on the season of the year and the frequency of jet cleaning should be adjusted accordingly.     

Recommendations for the market introduction of solar thermal power stations

Until 2010, solar thermal power stations based on parabolic trough concentrating collectors can become a competitive option on the world's electricity market, if the market extension of this mature technology is supported by a concerted, long-term programme capable of bundling the forces of industry, finance, insurance and politics. Technical improvements based on the experience of over ten years of successful operation, series production and economies of scale will lead to a further cost reduction of 50% and to electricity costs of 0.06 - 0.04 US$/kWh for hybrid steam cycles and hybrid combined cycles, respectively. Until 2010, a capacity of 7 GW will be installed, avoiding 16 million tons of carbon dioxide per year. The programme comprises an investment of 16 billion US$ and requires external funding of 6%.     

Influence of an ammonia activation prior to the PECVD SiN deposition on the solar cell performance

Silicon nitride (SiN) from plasma-enhanced chemical vapour deposition is widely used in PV industry as an antireflection coating. In addition the large amount of hydrogen (of up to 25 at%) (J. Appl. Phys. 49 (1978) 2473) incorporated in the SiN layer can be driven into the solar cell during the contact firing step, leading to an excellent bulk passivation as demonstrated by several research institutes during the last decade (Proceedings of the 12th EC PVSEC, Amsterdam, The Netherlands, 1994, p. 1018). Despite these advantages sometimes a problem occurs during the firing of the SiN layer, called blistering. Supposing that the blistering effect can be influenced by the surface preparation we performed a short ammonia plasma activation step prior to the SiN deposition. This step results in no damage of the surface which is shown in the form of solar cell results and lifetime measurements. On the contrary a positive effect on lowly doped emitters is possible.     

Steady-state performance of a grid-connected rooftop hybridwind-photovoltaic power system with battery storage

This paper reports the performance of a 4-kW grid-connected residential wind-photovoltaic system (WPS) with battery storage located in Lowell, MA, USA. The system was originally designed to meet a typical New-England (TNE) load demand with a loss of power supply probability (LPSP) of one day in ten years as recommended by the Utility Company. The data used in the calculation was wind speed and irradiance of Login Airport Boston (LAB) obtained from the National Climate Center in North Carolina. The present performance study is based on two-year operation. (May 1996-Apr 1998) of the WPS. Unlike conventional generation, the wind and the sunrays are available at no cost and generate electricity pollution-free. Around noontime the WPS satisfies its load and provides additional energy to the storage or to the grid. On-site energy production is undoubtedly accompanied with minimization of environmental pollution, reduction of losses in power systems transmission and distribution equipment, and supports the utility in demand side management. This paper includes discussion on system reliability, power quality, loss of supply and effects of the randomness of the wind and the solar radiation on system design     

Experimental study on the effect of dust deposition on solar photovoltaic panels in desert environment

The accumulation of dust particles deteriorates the performance of solar cells and results in appreciable losses in the generated power due to the sun irradiance scattering effects on the surface of the solar panel. This study investigates the impact of dust accumulation on photovoltaic solar modules in Baghdad city in Iraq. For this purpose an experiment has been conducted to quantify losses caused by the accumulation of dust on the surface of three identical photovoltaic solar modules. The modules have been installed with direct exposure to weather conditions, in a well controlled experimental setup. Subsequently, measurements of dust accumulation on modules have been taken on daily, weekly and monthly basis. The dust density and size distribution of aerosol particles and fibers have been also investigated and measured by a highly sensitive aerosols measuring system. The dusted module and another similar clean module have been then exposed to constant radiation and constant temperature using a solar simulator as light source. The deposition of the dust on the surface of the photovoltaic solar modules showed a reduction in both the short circuit current (I_sc) and the output power compared to the same parameters of the clean module. The average degradation rate of the efficiencies of the solar modules exposed to dust are; 6.24%, 11.8% and 18.74% calculated for exposure periods of one day, one week and one month. The experimental results are well compared with the calculations obtained by a theoretical model recently developed by the authors.     

集热棚高度对太阳能热气流发电性能的影响

以内蒙古乌海金沙湾太阳能烟囱热气流发电站为研究对象,应用ANSYS-Fluent软件对电站系统进行了稳态数值计算,模拟不同集热棚高度下系统内部流场和压力场的分布规律。模拟结果的对比分析显示,对该电站而言,集热棚高度以6⁸ m为宜。     

Evaluation of the development potential of rooftop solar photovoltaic in Taiwan

Because of extensive exploitation, fossil fuels are gradually becoming depleted and global warming issues are increasing. Therefore, all nations must develop alternative energy resources to reduce the potential risk of exhausting the available fossil fuel energy supply and to resolve environmental degradation.The amount of sunlight and installed power capacity are crucial factors that influence solar photovoltaic (PV) efficiency. Among domestic and international studies, numerous scholars have proposed various installed power capacity assessment models, which typically calculate areas based on sub-fields, ground floors or per capita. However, an evaluation of the potential of solar PV power generation on rooftops indicated that the shadow effect caused by building structures substantially influence the amount of installed power capacity. This study aims to effectively compute the shadow areas (shaded areas) on rooftops. By using the Hillshade module, the buildings' elevation data and the solar azimuth and altitude angles at different hours were calculated to obtain the hourly sun/shade grayscale values. The grayscale values were then integrated into binary images to calculate the shadow areas on rooftops.This study suggests that the rooftop solar photovoltaic installation capacity is some 12,428.5 MW and power generation capacity 15,423.75 GWh in Taiwan.     

Influence of solar heating on the performance of integrated solar cell microstrip patch antennas

The integration of microstrip patch antennas with photovoltaics has been proposed for applications in autonomous wireless communication systems located on building façades. Full integration was achieved using polycrystalline silicon solar cells as both antenna ground plane and direct current power generation in the same device. An overview of the proposed photovoltaic antenna designs is provided and the variation characterised of the electromagnetic properties of the device with temperature and solar radiation. Measurements for both copper and solar antennas are reported on three different commercial laminates with contrasting values for thermal coefficient of the dielectric constant.